Receive the latest national-international updates in your inbox

A New York state trooper testified Tuesday at Kerry Kennedy's drugged-driving trial that he was concerned she might have suffered a seizure or stroke after her car swerved into a truck in 2012.

Trooper Bradley Molloy said the daughter of the late Sen. Robert Kennedy passed several drug tests that he administered at the police station. The tests included having Kennedy follow the tip of a pen with her eyes, stand on one leg and touch the tip of her finger to her nose, Molloy said.

Testimony Begins at Kennedy Trial

Kerry Kennedy is accused of driving under the influence of Ambien two years ago, when she got into an accident on I-684 in Westchester County. Marc Santia reports. (Published Monday, Feb 24, 2014)

On Monday, a North Castle town police officer, Joel Thomas, said he had administered four field sobriety tests, involving eye movements, walking and turning, reciting part of the alphabet and standing on one leg. Kennedy only passed one, reciting the alphabet from J to T, he said.

Kennedy told the trooper that she had consumed some carrots and a cappuccino that morning and had slept about eight hours the night before. Molloy said Kennedy also told him she was concerned that she might have accidentally taken a sleeping pill instead of her thyroid medication. She said she had Ambien and the thyroid pills next to each other in her medicine cabinet.

Kerry Kennedy Arrested for Allegedly Driving Under the Influence of Drugs

"The defendant was not impaired by any drug," Molloy said. "I feel she may have suffered a medical condition while driving."

Molloy said Kennedy was polite and cooperative.

A forensic toxicologist testified later Tuesday that most people experience the effects of Ambien within 15 to 45 minutes of taking it. But Elizabeth Spratt, a prosecution witness who works for the Westchester County Department of Laboratories and Research, said it can take up to two hours for the drug to take effect.

Spratt said the effects include sleepiness, poor motor coordination and headaches. The drug can also cause amnesia, meaning that many people don't remember much after they've taken Ambien, she said.

Kennedy is the ex-wife of Gov. Andrew Cuomo and niece of President John F. Kennedy. Her mother, Ethel Kennedy, and a sister, Rory Kennedy, were both in the courtroom. Rory Kennedy took the stand as the defense began its arguments.

On Monday, motorists testified that Kennedy swerved her Lexus into a truck, damaging the car and blowing a tire, but kept driving and later was slumped at her steering wheel and disoriented.

In his opening statement, defense lawyer Gerald Lefcourt said Kennedy was not disputing that she drove erratically. But he said it happened because Kennedy accidentally took an Ambien sleeping pill that morning instead of her thyroid medication.

Prosecutor Stefanie DeNise said even if Kennedy took the sleeping pill accidentally, she violated the law by failing to stop when she felt its effects.